There have been two big myths about the “mighty” Raptor that I just need to talk about or write down before they make my head explode. Two of the biggest things that the designers aimed for were not met. At all. Part of it being a misnomer of sorts (to fool the less educated?) and the other being a rather persistent misunderstanding of certain concepts behind what makes an airplane go.
I never got my degree in Aeronautical Engineering, but I’ve had the “crash course” in the theory of flight and even that level of understanding leaves one confused as to why the Raptor was designed the way it was. For example, it’s common knowledge that of the four forces in flight, two are quite undesirable. Those being weight and drag, in which the Raptor is unacceptably sloppy. Of the other two, the only category that I can see it doing well in is lift. Maybe. And while it has a seemingly impressive amount of thrust, when compared to its weight that amount becomes a lot less impressive. But I digress, on to the mythbusting.
Supercruise: First, I need to lay down two very basic definitions of two very basic words, because somehow they seemed to escape the head honchos in all this. Super – In this case, it refers to flying supersonically. Very simple. Cruise – The speed at which the vehicle (car/airplane/hummingbird) is the most efficient. You go the farthest when cruising, while using the least amount of gas.
Still with me? Good. So what’s the problem? Well, the Air Force for whatever reason defines “Supercruise” as the ability to go supersonic in dry thrust alone. Other than completely missing the point, apparently they forgot that every other supercruiser ever built has done it with some form of afterburner. Ask Col. Riccioni about it. As one pilot put it to me, if they want to stay up a bit longer, they’ll keep it around .8-.9 Mach. Wait, what? I thought it cruised supersonically? That’s what supercruise MEANS. You mean to tell me that the Raptor is a SUBcruiser??? So much for that.
Range: So for some reason, no one in the design department of this thing knows what it is that makes a plane go far. It’s no secret, lots of people know exactly what does it, and thankfully those people were on the job when the Air Force needed the F-16. The Air Force tends not to think in the realm of the relative, which is exactly the reason why they continue to miss the point. It’s not the amount of fuel that determines range, it’s the RELATIVE fuel. In other words, the weight of the fuel divided by the total weight of the aircraft including the fuel. It’s the fuel fraction. That and the relationship between lift and drag (you know, if the engines have to work against a buttload of drag to get the necessary speed for the wings to generate enough lift to get the plane off the ground, they’re not being very efficient).
So now back to the point. The examples are everywhere about why the two criteria above are the determining factors to aircraft range. The YF-16 upon its unveiling not only had longer range than the larger F-15, but it had longer range than any other fighter in the Air Force. Before the AF got their grubby paws on it and crammed as much heavy crap on it as possible, it had a takeoff fuel fraction of .30+. The F-15 is somewhere around .28. For better examples, the extremely long-legged MiG-31 runs at about a .45, and the aircraft that made it around the world in one try had a fuel fraction of .75! So where does our airplane in question lie? A meagre .275, give or take. More likely take, because with every new “upgrade,” it just gets heavier. Around here they’re proclaiming it to be 80,000lbs!
So there you go, the next time someone talks about the F-22 being the longest-legged supercruiser in the world, you can immediately let anything else they say just fall right on out the other side of your head. Then wonder why you hang out with these people.
